Avoiding tomato blight organically in Ireland

Friday morning, my husband’s weather app came up with something that we both found confusing.

“There’s a blight warning for Ireland!” he told me, thinking it was bizarre.

I raised an eyebrow because I didn’t know this was still a thing. For me, potato blight is the stuff of history books and represents a very painful chapter in Irish history. Also, I’m not currently growing potatoes. And I didn’t know blight affected anything else. Surely, I thought, in this day and age, there’s a cure for it.

So I went to Met Eireann, the Irish Meterological Office, and checked what they said.

I thought this only affected potatoes so I wondered if I should plant mine out asap or leave them. See, in the past when I have a bag of shop-bought potatoes and they have started to sprout, I planted them in the ground and got a big crop of delicious new potatoes. Article here. I currently have a bag of sprouting potatoes in our veg drawer, and this week would be the perfect time to plant them, given that the end of June is really the last time you can plant anything in our climate if you want it to crop before winter.

I looked up how to avoid potato blight and found out it’s much worse than that. It also affects tomatoes. The two plants don’t just sound the same when Gene Kelly sings about them in Shall We Dance, they also are very closely related. So close, they get the same disease.

Even having to think about dealing with this feels like trying to deal with the plant equivalent of the Black Death, but I’ve done some research and here’s what I’ve found out.

There are two types of blight. Early blight, which affects North America earlier in the planting season, and late blight, which affects Ireland and southwest Britain. Remedies for early blight won’t work for late blight, because the diseases are two different species.

Once late blight takes hold, it cannot be cured. The first sign is the leaves are damaged, then your crops look… ill.

Farmers can spray their crops’ leaves aggressively with fungicides to keep the blight away. None of these seem to be available for homesteaders, smallholders or gardeners. I’m currently five months pregnant and so I don’t really want pesticides or other chemicals like that anywhere near me. I don’t even use weed killer.

Luckily, there are some steps you can take to prevent blight affecting your organic tomatoes without using any chemicals. It’s spread when wind carries spores during humid conditions followed immediately by rain. The goals are to keep the leaves off the soil and as dry as possible to protect the plants.

First, stake all your tomatoes up off the soil. I’m growing Tumbling Tom variety, which tends towards the ground, but I’ve found it’s not too hard to anchor them to a bamboo pole and get them to grow upwards.

Second, remove any leaves that grow close to the soil. Tomatoes have more leaves than they need, especially the lower ones where the plants don’t flower or produce fruit, so this pruning will not damage the plant but could save it.

If you have a greenhouse or shed, move your containerized tomatoes into it while conditions are good for the spread of blight. Consider growing your tomatoes in your greenhouse instead of your garden as this is the best way to keep them safe. You can also grow them in a polytunnel but I’m assuming if you had one, they’d already be under it.

If you don’t have a greenhouse, or your plants can’t be easily moved, get some polythene sheeting and make a DIY polytunnel to place over your tomato crops. Make supports for it from bamboo poles laid diagonally, so they meet at the top where you can tie them together (like an old-fashioned tent). Use a pair of four-foot bamboo poles roughly every 2-3 feet and lay the polythene over it. You can anchor the polythene with big stones or with tent pegs, if you have any.

If you can’t get hold of polythene sheeting or don’t want to use it, get a parasol or large umbrella (or a gazebo if you have one) and cover your tomatoes with it. It won’t be as effective as the other protective measures because the spores will still be in the air and an open-sided raincover won’t keep them out, but it will be better than nothing. The rain carries the fungus. Keeping the rain off the leaves will help protect the plants. Be aware of wind conditions, however, because high winds could damage or blow away a parasol, umbrella or gazebo.

If you’re really stuck, cover your plants with bin bags for the duration of any rain during the weather warning and be sure to take them back off before too long so the plants get enough sunshine. White bags would be better as they will let more light through and not overheat the plants (black bags will conduct heat more whereas white reflects heat). Given that I don’t have any of the above, this is what I’m going to end up doing. Be careful not to tie the bags too tightly around the stems in case it snaps the stems. Tomatoes at this time of year shouldn’t be as delicate as, say, courgettes but they don’t exactly have tree trunks, either.

When watering, water the soil, not the leaves. Take the sprinkler attachment off your hose or watering can and use a gentle flow of water, trying not to splash the plant at all. Again, the goal is to keep the leaves as dry as possible.

Our warning says blight will be hitting Munster, Connaught and Leinster later today or tomorrow, but won’t reach Ulster until Sunday or Monday, so I have some time to try and prevent my plants getting blighted. Honestly, if I’d known this was a potential issue I would have bought a variety of tomatoes that was blight-resistant or I would have kept them indoors instead of planting them out.

Of course, this leaves the issue of what on Earth to do with this bag of sprouted potatoes. Will they grow healthy or will they get blighted if I try to grow them now? I haven’t really got a place to plant them which is the only thing that has been stopping me. I know it’s a bit late in the year to grow them, anyway, and lots of people’s potatoes are cropping already; maybe this particular batch will just have to go on the compost instead of in the ground.

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